US President Donald Trump has called on NATO allies to commit to spending 4% of their GDP on defence

Members of the alliance have already committed to spending at least 2% of their GDP on defence by 2024 - with President Trump now claiming that goal should be doubled.

White House press secretary Sarah Sanders confirmed Mr Trump made the suggestion during a private meeting with other NATO leaders in Brussels today.

Currently, five members of the 29-member alliance reach the 2% goal, with that expected to increase to eight by the end of the year.

It's estimated that 15 members will reach the current spending goal by 2024.

However, in a tweet after today's meeting President Trump called on other nations to up their spending 'immediately'. 

What good is NATO if Germany is paying Russia billions of dollars for gas and energy? Why are there only 5 out of 29 countries that have met their commitment? The U.S. is paying for Europe’s protection, then loses billions on Trade. Must pay 2% of GDP IMMEDIATELY, not by 2025.

— Donald J. Trump (@realDonaldTrump) July 11, 2018

Responding to reports of President Trump's suggestion, NATO Secretary-General Jens Stoltenberg noted: "We have agreed that we're committed to the pledge increasing defense spending to 2%. So let's start with that."

Since taking office last year, the US President has repeatedly called on NATO allies to up their defence funding.

Earlier, President Trump accused Germany of being a Russian “captive” - claiming an “inappropriate” gas deal had left Berlin “totally controlled” by Moscow.

German Chancellor Angela Merkel later responded, saying: "I've experienced myself a part of Germany controlled by the Soviet Union.

"I'm very happy today that we are united in freedom as the Federal Republic of Germany and can thus say that we can determine our own policies and make our own decisions and that's very good."

Additional reporting by IRN